Unhandled promise rejection

Question

The code below gives me the exceeds allowance or always failing transaction error but when i check my contract on remix i can see that the transaction goes through, makes the correct state changes and works as expected. In The assignment executionMetrics becomes undefined. I've been sitting trying to figure out the problem for 4hrs and I'm completely stuck. Anyone knows what's going on?

async function someAsyncFunc(){
  bookingPromiseArr = []
  let promise = instance.methods.bookTrip(tripKey).send({
    from: accounts[0],
    gasPrice: GAS_PRICE,
    value: 1,})
  bookingPromiseArr.push(promise)
  let executionMetrics = await executePromises(bookingPromiseArr, txStartTime)
}

async function executePromises(promisesArr, txStartTime) {
  await Promise.all(promisesArr)
    .then((receipts) => {
      let totalGasUsed = 0
      let txElapsedTime = Date.now() - txStartTime
      let lastBlock = receipts[receipts.length - 1].blockNumber
      receipts.forEach((receipt) => {
        totalGasUsed += receipt.gasUsed
        lastBlock =
          receipt.blockNumber > lastBlock ? receipt.blockNumber : lastBlock
      })
      // I've console logged here and seen that I've reached this point
      return {
        txElapsedTime: txElapsedTime,
        totalGasUsed: totalGasUsed,
        lastBlock: lastBlock,
      }
    })
    .catch((error) => {
      console.log('multipleTX():', error)
      process.exit(1)
    })
}

The smart contract function invoked:

function bookTrip(uint256 key) external payable requireTrip(key) nonBookedPassenger(key){
        Trip storage trip = trips[key];
        trip.passengers[msg.sender] = trip.price;
        trip.passengerCount++;
        emit LogNewTripPassenger(msg.sender, key, trip.price);
    }

Error log:

(node:23524) UnhandledPromiseRejectionWarning: Error: gas required exceeds allowance (8000029
) or always failing transaction
    at C:\Users\Diddi\Documents\mjukvaruteknik\examensarbete\tqdt33\node_modules\@truffle\hdw
allet-provider\node_modules\web3-provider-engine\subproviders\provider.js:18:36
    at XMLHttpRequest.request.onreadystatechange (C:\Users\Diddi\Documents\mjukvaruteknik\exa
mensarbete\tqdt33\node_modules\web3-providers-http\src\index.js:96:13)
    at XMLHttpRequestEventTarget.dispatchEvent (C:\Users\Diddi\Documents\mjukvaruteknik\exame
nsarbete\tqdt33\node_modules\xhr2-cookies\xml-http-request-event-target.ts:44:13)
    at XMLHttpRequest._setReadyState (C:\Users\Diddi\Documents\mjukvaruteknik\examensarbete\t
qdt33\node_modules\xhr2-cookies\xml-http-request.ts:219:8)
    at XMLHttpRequest._onHttpResponseEnd (C:\Users\Diddi\Documents\mjukvaruteknik\examensarbe
te\tqdt33\node_modules\xhr2-cookies\xml-http-request.ts:345:8)
    at IncomingMessage.<anonymous> (C:\Users\Diddi\Documents\mjukvaruteknik\examensarbete\tqd
t33\node_modules\xhr2-cookies\xml-http-request.ts:311:39)
    at IncomingMessage.emit (events.js:228:7)
    at endReadableNT (_stream_readable.js:1185:12)
    at processTicksAndRejections (internal/process/task_queues.js:81:21)
(node:23524) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error origin
ated either by throwing inside of an async function without a catch block, or by rejecting a
promise which was not handled with .catch(). (rejection id: 1)
(node:23524) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In th
e future, promise rejections that are not handled will terminate the Node.js process with a n
on-zero exit code.
TypeError: Cannot read property 'txElapsedTime' of undefined
    at multipleTx (C:\Users\Diddi\Documents\mjukvaruteknik\examensarbete\tqdt33\client\cl-int
eraction\contractInteract.js:65:24)
    at processTicksAndRejections (internal/process/task_queues.js:94:5)
    at test (C:\Users\Diddi\Documents\mjukvaruteknik\examensarbete\tqdt33\client\cl-interacti
on\profile1.js:26:5)

Answer 1

As goodvibration pointed out in his comments this wasn't a ethereum or web3 problem but a pure javascript/basic programming error. The big mistake in the code was returning in the then()-statement and assuming that it would be the return value for executePromises(). That wasn't the case and i have corrected it.